1. Field of the Invention
The present invention relates in general to an M6 block cipher system and a method for encoding content and performing authentication of a device.
2. Description of the Related Art
If various forms of audio/video data (hereinafter referred to as content) are transmitted by a data bus, it is possible for a third party to intercept or tamper with the content. Even if an IEEE 1394 high-performance bus is used, interception and/or tampering with the content may still be possible. However, a digital transmission content protection (DTCP) specification volume 1.3, proposed by Hitachi, Intel, Matsushita, Sony and Toshiba, provides a cryptographic protocol for content protection from external attacks.
In order to protect content from external attacks, a M6 block cipher algorithm is used for DTCP. A general M6 block cipher algorithm generates a random number, creates an exchange key and encodes content, which may be necessary processes for the content authentication between reception and transmission devices. A general M6 block cipher algorithm system contains two cores for respectively encoding content and authenticating the device. The general M6 block cipher algorithm system may be divided into M6-S56 and M6-KE56 algorithms. The M6-S56 algorithm is a block cipher algorithm used to encode content, and the M6-KE56 algorithm is a block cipher algorithm used to authenticate a device. The M6 block cipher algorithm supports a 64-bit block having a 56-bit key and composed of 10 rounds in total.
A conventional cipher algorithm implements a M6-S56 converted cipher-block chaining (C-CBC) cipher of the M6 block cipher algorithm used for the DTCP. However, the conventional art does not use the M6-KE56 algorithm to generate a random number and create the exchange key for authentication. In addition, the conventional art does not describe nor suggest using a round function or a Pi function for the implementation of M6-S56. Further, a general M6 block cipher algorithm system contains two cores for respectively encoding content and authenticating the device.